Liquid crystal displays (LCDs) generally have advantages of lightness in weight, a thin profile, flexible sizing, and low power consumption. For these reasons, LCDs are widely used in products such as laptops, personal digital assistants, mobile phones, and so on.
Referring to FIG. 9, this is a top view of a part of a display panel 10 of a conventional liquid crystal display. The display panel 10 includes a plurality of parallel gate lines 15 and a plurality of parallel data lines 16. The plurality of gate lines 15 and the plurality of data lines 16 are insulated from and cross each other, thereby cooperatively defining a plurality of pixel units (not labeled). Each pixel unit includes a thin film transistor 20, and a pixel electrode 27 connected to the thin film transistor 20. The thin film transistor 20 is connected to a corresponding one of the gate lines 15, and to a corresponding one of the data lines 16.
Referring also to FIG. 10, this shows a cross-sectional view of part of the display panel 10, corresponding to line X-X of FIG. 9. The display panel 10 includes a first substrate 11, a second substrate 12 arranged opposite to the first substrate 11, and a liquid crystal layer 13 interposed between the substrates 11, 12. A plurality of spacers 17 is disposed between the first substrate 11 and the second substrate 12, thereby maintaining a consistent cell gap. A common electrode 14 is disposed on an inside of the first substrate 11. The gate lines 15 are disposed on the second substrate 12, and the pixel electrodes 27 are disposed at the second substrate 12 and insulated from the gate lines 15. The gate lines 15 are overlapped by corresponding portions of the common electrode 14.
Referring also to FIG. 11, this shows a cross-sectional view of part of the display panel 10, corresponding to line XI-XI of FIG. 9. The data lines 16 are formed at an inside of the second substrate 12, and the pixel electrode 27 is insulated from the data lines 16. The data lines 16 are overlapped by corresponding portions of the common electrode 14.
Referring also to FIG. 12, this shows an equivalent circuit diagram of an exemplary one of the thin film transistors 20. The thin film transistor 20 includes a gate 21, a source 22, and a drain 23. The gate 21 is connected to the corresponding gate line 15, the source 22 is connected to the corresponding data line 16, and the drain 23 is connected to the pixel electrode 27. A parasitic capacitor 28 formed by the gate line 15 and the overlapping portion of the common electrode 14 is connected to the gate line 15. A parasitic capacitor 29 formed by the data line 16 and the overlapping portion of the common electrode 14 is connected to the data line 16.
When the display panel 100 is operating, firstly, a gate voltage A is transferred to the gate 21 through the gate line 15. The source 22 is connected to the drain 23 if the voltage A is larger than a threshold voltage of the thin film transistor 20. Secondly, if the source 22 is duly connected to the drain 23, a data voltage B is transferred to the source 22 through the data line 16, and begins to charge the pixel electrode 27 through the drain 23. If the voltage A is less than the threshold voltage, the source 22 is disconnected from the drain 23. The potential difference between the pixel electrode 27 and the common electrode 14 changes the tilt angle of liquid crystal molecules of the liquid crystal layer 13 at the pixel unit. Thereby, a desired amount of light transmission occurs at the pixel unit, and all the pixel units cooperate to make up an image that is displayed on a screen of the display panel 10.
The gate voltage A charges the parasitic capacitor 28 before being transferred to the gate 21, and the data voltage B charges the parasitic capacitor 29 before being transferred to the data 22. Therefore, signal distortion and delay are liable to occur during the transference of these voltages. These problems can in turn cause image flickering and impairment of the quality of images displayed on the screen.
Accordingly, what is needed is a liquid crystal display configured to overcome the above-described problems.